.carousel-img-mask {
    background: rgba(0, 0, 0, .4);
    width: 100%;
    height: 100%;
    position: absolute;
    top: 0;
    left: 0;
}

/*移动端适配*/
@media (max-width: 576px) {
    .carousel-img-mask {
        background: rgba(0, 0, 0, 0);
    }
}